Club Cobra Keith Craft Motorsports  

Go Back   Club Cobra > Engine Building, Tuning, and Induction > Small Block Talk

Welcome to Club Cobra!  The World's largest non biased Shelby Cobra related site!

  •  » Representation from nearly all Cobra/Daytona/GT40 manufacturers
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and nearly 1 million posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

MMG Superformance
Nevada Classics
Keith Craft Racing
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
MMG Superformance
MMG Superformance
Advertise at CC
Banner Ad Rates
MMG Superformance
Keith Craft Racing
MMG Superformance
January 2018
S M T W T F S
  1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31      
  #1 (permalink)  
Old 01-13-2018, 07:39 AM
CC Member
Visit my Photo Gallery

 
Join Date: Oct 2017
Posts: 15
Not Ranked     
Default Roush 402 R Oil pump question!

Hello!

I just bought a bdr cobra with a roush 402R engine in it. I just need to know what are the problems for a low oil pressure? The engine runs on new 10w40 Motoroil and the gauge shows 30 psi at start. After a while, when the oil gets warmed up it drops to about 22 psi. I heard it could be a bad ground cable of the gauges. I have to look at the oil pump if I can see a problem! Where should I start to look at first. The engine runs normal, but i stopped the engine when the pressure droped. Do you guys know, what kind of oil pump this engine needs, just in case if I need a new one. Would be happy to get some informations about this motor!
Thanks from germany!
Marc
Reply With Quote
Sponsored Links
Sponsored Links
  #2 (permalink)  
Old 01-13-2018, 09:41 AM
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Location: Louisville, KY
Cobra Make, Engine: I'm Cobra-less!
Posts: 8,901
Send a message via AIM to blykins
Not Ranked     
Default

What's wrong with 22 psi hot at idle?

Does the oil pressure go up with rpm? If so, I wouldn't try to fix a problem that doesn't exist.
__________________
www.lykinsmotorsports.com
Reply With Quote
  #3 (permalink)  
Old 01-13-2018, 04:23 PM
mln385's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Cobra Make, Engine: BDR
Posts: 495
Not Ranked     
Default

I am pretty sure 10w30 is the recommend oil for that series motor.
Reply With Quote
  #4 (permalink)  
Old 01-14-2018, 05:09 AM
Gaz64's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2008
Location: Brisbane, QLD
Cobra Make, Engine:
Posts: 1,513
Not Ranked     
Default

Quote:
Originally Posted by blykins View Post
What's wrong with 22 psi hot at idle?

Does the oil pressure go up with rpm? If so, I wouldn't try to fix a problem that doesn't exist.
Exactly.

Dropping from from 30 psi cold to 22 psi hot is perfect.

Many other engines have larger pressure changes.

What pressure does the engine have at 3000 rpm hot?
Reply With Quote
  #5 (permalink)  
Old 01-14-2018, 07:45 AM
CC Member
Visit my Photo Gallery

 
Join Date: May 2006
Location: St. Louisville, Oh
Cobra Make, Engine: A&C 67 427 cobra SB
Posts: 1,929
Not Ranked     
Default

The first thing I would do is connect a mechanical gauge to the engine and verify the gauge in the car is reading correctly. If they are within 5 psi of each other at idle and revved up, note if the gauge in the car is a little high or a little low.

Even assuming your gauge is correct, 20 psi at idle wouldn't bother me, as long as the pressure goes up to 50 or more at high rpm. 15 psi at idle might not actually be a problem but that is getting low. I have had old worn out engines idle clear down to 5 psi and still run another 50K miles, with no problems. If your pump is the standard volume pump, 20ish is normal. If it is a high volume pump, I would expect more, but not be overly concerned.

Do not go to 10-30 if the pressure is already low with 10-40.

If you have low oil pressure odds are that it is something other than the oil pump. Oil pumps rarely go bad unless they are starved for oil. I would be making sure any external oil filter plumbing or oil cooler was done correctly.

Usually low oil pressure is caused by loose bearing clearances. When I was a puppy, the racing crowd purposely set bearing clearances loose an ran heavy oil. Now the trend is to set bearings tight and run thin oil. I think the latter is better, but the fact is both strategies work. If my oil pressure dropped below 15 at an idle, I would put in heavier oil and run it, as long as there were no other signs of problems.

Last edited by olddog; 01-14-2018 at 07:56 AM..
Reply With Quote
  #6 (permalink)  
Old 01-14-2018, 01:29 PM
CC Member
Visit my Photo Gallery

 
Join Date: Oct 2017
Posts: 15
Not Ranked     
Default

The motor has 13000 miles on it! Roush says 25-30 psi on idle! On the data sheet of the motor it shows something between 55-60psi from 3000-6000rpm.
I talked to other people with 402r roush engines and they have also the pressure from 55-60 psi. I can‘t believe that the oil pump has a problem, because of the low miles. I will test it with a manual pressure tester!
Thanks for help.
Reply With Quote
  #7 (permalink)  
Old 01-15-2018, 08:24 AM
WardL's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Sep 2009
Location: Camarillo, CA
Cobra Make, Engine: SPF #2608, Roush 427SR T-W
Posts: 908
Not Ranked     
Default

Roush recommends straight 30W oil. Your pressures might be normal with the heavier oil.
Reply With Quote
  #8 (permalink)  
Old 01-15-2018, 09:51 AM
mln385's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Cobra Make, Engine: BDR
Posts: 495
Not Ranked     
Default

Quote:
Originally Posted by WardL View Post
Roush recommends straight 30W oil. Your pressures might be normal with the heavier oil.
Is this via a conversation? Their literature and my tag says 10W30 427 R Crate Engine

I have a 427 and the link is for same but I do have an original catalog with the 402R and they recommend the same.
Reply With Quote
  #9 (permalink)  
Old 01-15-2018, 04:01 PM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2007
Location: Carlsbad, Ca
Cobra Make, Engine: SPF 2932 with 438 Lykins Motorsports engine. Previous owner of FFR 5452.
Posts: 2,371
Not Ranked     
Default

Roush recommends 10w30.

Try 20w50 non synthetic and see where your pressure goes.
My Roush 427sr ran 45-50 lbs at startup and then settled around 42 lbs when cruising warm. Hot idle was around 35lbs at an idle speed of 900 rpm. This was with 10w30 royal purple synthetic oil. And then the engine destroyed itself.
__________________
Jim
Reply With Quote
  #10 (permalink)  
Old 01-15-2018, 04:38 PM
mln385's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 2001
Cobra Make, Engine: BDR
Posts: 495
Not Ranked     
Default

Quote:
Originally Posted by jhv48 View Post
Roush recommends 10w30.

Try 20w50 non synthetic and see where your pressure goes.
My Roush 427sr ran 45-50 lbs at startup and then settled around 42 lbs when cruising warm. Hot idle was around 35lbs at an idle speed of 900 rpm. This was with 10w30 royal purple synthetic oil. And then the engine destroyed itself.
Do you know what the cause of the failure was?
Reply With Quote
  #11 (permalink)  
Old 01-16-2018, 02:07 AM
Gaz64's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2008
Location: Brisbane, QLD
Cobra Make, Engine:
Posts: 1,513
Not Ranked     
Default

In these days of multigrade oils, why would one run a single viscosity oil?

Depending on how the engine is clearanced is a high determining factor in oil viscosity selection.

30W cold is thicker than the majority of current multigrades.

And then when hot is thinner than most.

Oil flow with a thin oil is more important than low flow with a thick oil.
Reply With Quote
  #12 (permalink)  
Old 01-16-2018, 09:18 AM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2007
Location: Carlsbad, Ca
Cobra Make, Engine: SPF 2932 with 438 Lykins Motorsports engine. Previous owner of FFR 5452.
Posts: 2,371
Not Ranked     
Default

Quote:
Originally Posted by mln385 View Post
Do you know what the cause of the failure was?
Valve guides worn, cylinders scored, piston cracked, bearings shot. excessive oil consumption. No single cause. At 13,000 miles it looked like it had 100,000 hard miles when we tore it apart. Needed a complete rebuild.
__________________
Jim
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 04:22 AM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink